Tenacity
Solubility
Durability
Specific Gravity
Fracture
Cleavage
Mohs Hardness
Chemical Composition
Subconchoidal, Conchoidal
(Fe,Mg,Zn) 2Al 9(Si,Al) 4O 22(OH) 2Ulrich Henn and Claudio C.
Uneven, Subconchoidal, Splintery
Good on {110}, poor on {100}
Al 2SiO 5Michael OâDonoghue , Gems, Sixth edition (2006) More from other references